[Journal of Experimental Biology] Tardigrades are tiny ecdysozoans – creatures that grow by shedding their cuticle – with approximately 1500 species that have spread across the planet, from the ocean sediments to mountain tops, ranging in size from 50 μm up to 1.2 mm.
The animals have 4 pairs of legs, and graze on microscopic organisms, including bacteria, algae, nematodes, rotifers and other tardigrades. But they can only remain active on land when enveloped in water, often living in rain gutters, lichens and moss, giving rise to one of their common names, moss piglets.
As soon as the water dries up, the tiny creatures go into a form of suspended animation, known as cryptobiosis, until the water returns, when they resuscitate and continue on their way. The animals are so robust that they have even been sent into space, surviving extreme cold, radiation and lack of oxygen.
Nadja Møbjerg, University of Copenhagen, Denmark, has been investigating the remarkable resilience of these extraordinary microscopic creatures for almost 30 years. She tells Journal of Experimental Biology how these tiny creatures survive without a heart and lungs and how they endure the most extreme environments.
Extraordinary Creatures: Tardigrades, Journal of Experimental Biology (open access)
Astrobiology, extremophile,
